为定量认识并寻找可能方法来弥补或修正目前常用的水洗－滤膜法测定植物叶面滞尘能力的不足，更加直观和准确地反映叶面滞尘能力，选择北京市相对清洁的北京植物园和污染严重的国贸桥2个地点，利用环境扫描电镜测定了大叶黄杨（ Euonymus japonicas ）、国槐（ Sophora japonica ）、毛白杨（ Populus tomentosa ）、银杏（ Ginkgo biloba）和紫叶李（Prunus cerasifera）5个树种的上、下叶表面滞留的颗粒物（PM）数量和粒径组成，计算出单位植物叶面积滞尘量，并与水洗－滤膜法进行比较。结果表明：植物叶面滞留的颗粒物数量以PM＜10（粒径＜10μm的颗粒物）为主，占总数的90％以上；污染严重的国贸桥叶表滞留的PM＜2�5数量高于相对清洁的北京植物园；采用颗粒物计数法与水洗－滤膜法测定得到的叶面滞尘量之间存在显著线性关系，但两者数值相差很大。有必要进行严格的控制实验来确定导致差异的主要原因与机制，并藉此提出水洗－滤膜法的修正技术或发展多种方法的联合运用技术。%Since the current washing⁃membrance⁃filtering method is not good enough to determine dust⁃retaining capacity of plant leaves, it is essential to quantitatively define some new potential methods to make up or amend shortages of the current method and to determine intuitively and accurately dust⁃retaining capacity of plant leaves. Two sampling sites, the Beijing Botanical Garden and Guomao Bridge, in Beijing were selected. The former is relatively clean and the latter severe⁃ly polluted. Leaves were collected from Euonymus japonicas, Sophora japonica, Populus tomentosa, Ginkgo biloba and Prunus cerasifera in the two sites in Beijing for determination of quantity and particle⁃size composition of particulate matter ( PM) detained on the upper and lower surfaces of the leaves with a scanning electron microscope and then quantity of de⁃tained PM per unit leaf area was calculated for comparison with that obtained by the washing⁃membrance⁃filtering method. It was found that the PM on leaf surfaces was dominated by the PM<10( PM with diameter less than 10μm) , which accoun⁃ted for over 90% of the total quantity of particles. The leaf surfaces of the investigated trees growing at the heavily polluted site ( Guomao Bridge) had more PM<2�5 detained than those at the less polluted site ( Beijing Botanical Garden) did. A significant linear relationship was observed between the counting method and the washing method in PM mass obtained. However, the difference between the two was very sharp. The PM mass obtained with the washing method was only about 9% as high as that with the counting method. It is, therefore, essential to design and conduct more strictly controlled ex⁃periments to determine causes and affecting factors of this big difference, and also to develop techniques for calibrating the current washing methods, or multi⁃approach combined application techniques.
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